Enhanced Ionic Conductivity of Composite Solid Electrolyte by Defective Li1.3Al0.3Ti1.7(PO4-y)3 for Solid-State Li-ion Batteries

Oxygen-deficient Li1.3Al0.3Ti1.7(PO4)3 (LATP) was prepared using a hydrothermal method followed by hightemperature calcination. Comprehensive analyses using X-ray powder diffraction (XRD), electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) conclusively demonstrated the successful preparation of oxygen-deficient LATPs under different calcination temperatures in an argon-hydrogen mixed atmosphere. These varying temperatures affected the concentration of oxygen defects in LATP. The hydrothermal precursor was calcined at 700 degrees C for 6 h to prepare an oxygen-deficient LATP, which was subsequently combined with polyacrylonitrile (PAN) to form a solid composite electrolyte. The composite exhibited a total ionic conductivity of 7.55 x 10-4 S cm- 1 at 20 degrees C. Furthermore, when tested at 25 degrees C with a current density of 0.025 mA cm -2, the composite displayed good compatibility with a lithium metal anode. At a current density of 0.1 C, the initial discharge capacity was found to be 256.2 mA h g- 1, which was maintained at 231.8 mA h g-1 after 100 cycles within the voltage range of 2.0-4.5 V. By judiciously modulating the oxygen defects concentration, it is possible to not only improve the ionic conductivity of the solid composite electrolyte but also to further enhance its discharge capacity.